The invention is based on a fuel injection valve and on a method for producing outlet openings in valves.
From German Patent Disclosure DE 196 36 396 A1, a fuel injection valve is already known that, downstream of its valve seat face with which a valve closing body cooperates to open and close the valve, has a perforated disk. This cup-shaped perforated disk, shaped from a metal sheet, has many ejection openings, through which the fuel is output, for instance into an intake tube of an internal combustion engine in the direction of an inlet valve. These ejection openings are made in the perforated disk by stamping, erosion or laser beam boring. The ejection openings have a continuous constant circular or elliptical cross section over their axial length.
The fuel injection valve according to the invention has the advantage that in a simple, economical way, a very wide range of variation in terms of flow rates, stream angles and spray properties is attainable. Advantageously, fluctuations in the stream angle are reduced. Moreover, structurings of the stream or spray and the creation of solid- and hollow-conical streams can be achieved more simply, even at high combustion chamber counterpressure, than in known fuel injection valves.
It is advantageous that with the fuel injection valve of the invention, a very high atomization quality of a fuel to be ejected can be attained, as well as shapings of the stream or spray that are adapted to given requirements (such as installation conditions, engine configurations, cylinder recesses, spark plug positions). As a consequence, with such an injection valve, among other things exhaust emissions of the engine can be attained, and a reduction in fuel consumption can also be achieved.
Especially in eccentric outlet openings, in which the center point of the inlet plane is not located on the longitudinal axis of the valve, it is advantageous if the inlet portion of the outlet opening has a relatively small opening width, and the outlet region is then markedly widened. In this way, even with such valves, advantageously small diameters for the valve seat face can be adhered to. Compared with known valves of the same design with eccentric outlet openings, the static hydraulic closing load can be decreased, and the tightness at the valve seat can be improved.
It is especially advantageous if the fuel is subjected to a swirl upstream of the outlet opening, because then in the contoured outlet region of the outlet opening, local accumulations of fuel are effectively achieved, which in the form of strands are desirable, especially for direct injection of fuel into a combustion chamber.
The method of the invention has the advantage that with it, in a simple way, a fuel injection valve can be produced with which the aforementioned advantages are attainable.
By the provisions recited in the dependent claims, advantageous refinements of and improvements to the method defined by claim 11 and claim 17 are possible.
Because of the high precision, in particular of the laser contour cutting, very exact outlet regions can be recessed, as a result of which the stream angle fluctuations of the ejected fuel spray can be reduced. The shaping of the outlet regions of the outlet openings by means of laser or electron beam erosion is extremely flexible, especially in comparison with mechanical embossing with embossing dies, for instance. For instance, outlet regions of outlet openings can easily be produced that are polygonal, that widen or taper in the form of a truncated pyramid in the flow direction, that have a circular or elliptical cross section, that widen or taper frustoconically in the flow direction, that are curved in convex or concave fashion, or that are embodied in stepped form with multiple portions.